<template>
  <div class="category-list">
    <ul>
      <li
        v-for="(category, index) in categories"
        :key="category.id"
        :class="{ active: activeIndex === index }"
        @click="selectCategory(index)"
      >
        {{ category.name }}
      </li>
    </ul>
  </div>
</template>

<script>
export default {
  data() {
    return {
      activeIndex: 0,
      categories: [
        { id: 1, name: '台式电脑' },
        { id: 2, name: '笔记本电脑' },
        { id: 3, name: '平板' }
      ]
    }
  },
  methods: {
    selectCategory(index) {
      this.activeIndex = index
      this.$emit('category-change', this.categories[index].id)
    }
  }
}
</script>

<style scoped>
.category-list {
  width: 30%;
  background-color: #f4f4f4;
  overflow-y: auto;
}
.category-list ul {
  list-style: none;
  padding: 0;
  margin: 0;
}
.category-list li {
  padding: 15px;
  cursor: pointer;
}
.category-list li.active {
  background-color: #dcdcdc;
}
</style>
